As disclosed, e.g., in U.S. Pat. Nos. 3,244,758 (Eberhardt) and 4,179,580 (Cobb) and in European Patent 128001 (Kudoh et al.), it is known that supported alkali metals, including potassium and sodium-potassium alloys, are useful as catalysts in the coupling of ethylenically-unsaturated hydrocarbons with aromatic hydrocarbons having an active hydrogen on a saturated alpha-carbon. The supported alkali metals are more effective than the corresponding unsupported alkali metals in such reactions but are still not as effective as might be desired.
U.S. Pat. No. 4,620,056 (Shimizu et al.) teaches that the catalytic activity of unsupported sodium metal in such coupling reactions can be increased by conducting the reactions in the presence of a combination of a styrene-type compound and a potassium compound, such as potassium hydroxide, as co-catalysts.
Pines et al., Journal of the American Chemical Society, Vol. 80, pp. 6001-6004 (1958) disclose the use of sodium hydroxide as a promoter for the sodium-catalyzed side chain aralkylation of alkylbenzenes with styrene.